a) Field of the Invention
The present invention relates to a method of manufacturing a golf club head, having a face line, a club number display and a logo mark on a surface thereof.
b) Prior Art
A golf club is made up of a head and a shaft, and it is typically classified into three groups, i.e., a wood, an iron and a putter. The iron and wood are classified according to the loft angle. For the iron, for example, a small loft angle (for example 20xc2x0 to 30xc2x0) iron is referred to as a long iron, while a large loft angle (for example 40xc2x0 to 50xc2x0) iron is referred to as a short iron. Normally, irons are numbered from the long iron to the short iron, for example from No.1 to No.9, and then there is a PW (pitching wedge), a SW (sand wedge), and etc. These numbers and symbols are generally called club numbers, attached to respective club heads.
Iron club heads are formed from iron or other various kinds of metallic materials. Whilst wood club heads were formed from wood materials such as persimmon in the past, they are mainly formed from metallic materials in recent years, such as so-called metal wood.
In general, methods for manufacturing a metallic golf club head are classified into two categories, i.e., casting and forging. Forging is superior to casting in that it can produce a golf club head of higher strength. Forging is a method by which a golf club head of a desired shape can be obtained by heating a metallic round rod material first, and then hammering it with a press or a hammer, using a die to thereby subject it to plastic deformation. In the broad sense of the term, xe2x80x9cforgingxe2x80x9d includes deep drawing as well in which a rolled metallic plate is die cut and then subjected to deep drawing.
In golf club heads manufactured by plastic forming such as forging, a face line provided on a face, a club number marking provided on a sole surface or the like and a logo mark provided on a sole, back, hosel or the like, are each formed by press forming, using a die or a stamp. For example, a face line is formed, using a linear die, while club number marking and logo mark are formed, using an impressing stamp.
For such press forming, a receiving die for rigidly retaining a golf club head against the pressing force is required. Further, as golf clubs have different configurations per each product and club number, respective specific receiving dies, corresponding to the respective linear dies and impressing stamp dies, must be prepared in addition to such linear dies and impressing stamp dies. Furthermore, as club heads of the same club number sometimes define slightly different configurations per each production lot number, there occurs a problem that the use of a receiving die that does not fit in with the configuration of a certain head could damage products or cause irregular face lines to be formed, so that it has been necessary to modify the receiving die every time the production lot number changes. Accordingly, the manufacture and modification of linear dies, impressing stamp dies and receiving dies have been too expensive and too time consuming.
In recent years, golf clubs of complex configurations have appeared to pursue a higher performance, some of which have too complex configurations to be received by a receiving die. If such golf clubs are forcedly received by a receiving die, die marks or scars would be inevitably produced so that it would be necessary to carry out a grinding process to clear away such die marks or scars. As a result, there has been a problem that production process and method are subject to many restrictions. Besides, as metallic materials having high hardness or low toughness are not suitable for cold press, there has been a problem that it is difficult to form face lines or the like in the case that such materials are used.
One of solutions for solving the above-mentioned problem is disclosed in Japanese Un-Examined Publication No.6-305241, in which a surface of a golf club head is irradiated with laser beam so as to change the color tone of a portion that was irradiated with laser beam on the surface of the club head, whereby suitable marking is carried out. According to such conventional marking method, however, the marking on a sole surface or the like is liable to be easily worn away due to the frictional contact with the earth. Further, whilst a face line needs to be formed as a concavity in order to apply spin to a ball, a face line formed by the above conventional marking method merely varies the color tone of the surface of a club head, and thus such face line is of no use.
To eliminate the above-mentioned problems, it is, therefore, a main object of the present invention to provide a method of manufacturing a golf club head
To attain the above object, there is provided, in accordance with an embodiment of the invention, a method of manufacturing a golf club head, having a face formed on a front and a shaft attachment portion formed on one side, wherein a concave portion is formed on a surface of said golf club head, using a laser beam processing machine.
Accordingly, it is possible to form a concave portion on a surface of the golf club head without conventional press-forming process. Thus, impressing stamp dies or receiving dies for a specific product or club number are no longer required, thereby saving costs and labor required for the manufacture or modification of those dies. Further, it is possible to form a concave portion without being affected by the configuration or material of a golf club head.